18 4⁻¹⁰⋅4⁹/4⁻¹;

18. $$\frac{4^{-10} \cdot 4^9}{4^{-1}} = \frac{4^{-10+9}}{4^{-1}} = \frac{4^{-1}}{4^{-1}} = 4^{-1-(-1)} = 4^{-1+1} = 4^0 = 1 $$.

Ответ: 1